Final answer:
The statement attributed to Sullivan about pre-adolescent need for intimacy leading to loneliness is false. Erikson spoke about the importance of developing a sense of self in adolescence before entering intimate adult relationships, while adolescents experience an increasing importance of peer and romantic relationships.
Step-by-step explanation:
The statement 'Sullivan (1953) stated that the pre-adolescent need for intimacy can lead to full-blown loneliness' is false. It was Erikson who discussed stages of psychosocial development and indicated that during early adulthood (20s through early 40s), the challenge is navigating intimacy versus isolation.
Erikson stressed the importance of developing a sense of self during adolescence before entering into intimate relationships in adulthood. Failure to form a positive self-concept can result in feelings of loneliness or emotional isolation.